Effects Of Salt Stress On Growth And Physiological Biochemical Characteristics Of Several Medicinal Plants

With the development of population growth and economic globalization,environmental problems became more and more serious.Soil salinization is a global problem which people pay more and more attention.In China,a lot of the saline soil widely distributed,and Jiangsu province has the largest coastal area,around 687000 hectares and increases nearly 1333 hectares every year.Saline soil is one of the most important agricultural resources in Jiangsu.Chinese herbal medicine is one of the excellent cultural heritages,which is important means for disease prevention and disease treatment.Screening the appropriate Chinese herbal medicine planting in saline soil not only can improve the ecological environment and the medicinal value of Chinese herbal medicine,but also promote the development of local economy and increase the income of native people.This study tried to plant four kinds of Medicinal plant:Silybum marianum(L.)Gaertn.,Mentha haplocalyx Briq.,Coix lacryma-jobi L.and Salvia miltiorrhiza Bge.,and select the high germination rate among them,and research the planting pattern in the simulation of saline environments,explore their physiological and biochemical characteristics of salt stress.The results obtained were listed as follows:1、Silybum marianum(L.)Gaertn.,Mentha haplocalyx Briq.,Coix lacryma-jobi L.,Salvia miltiorrhiza Bge could generally adapt to soil salinization.Based ongermination rate and germination period,we selected Silybum marianum(L.)Gaertn.and Mentha haplocalyx Briq.as the object of this study.2.When concentration of NaCl was too high(more than 14.4g/LNaCl,18g/LNaCI),Silybum marianum(L.)Gaertn.and Mentha haplocalyx Briq.could not survive,that is,the survival rate was 0%.Under the low concentration of NaCl(1.8g/LNaCl,3.6g/LNaCl)treatment,the above-ground and under-ground fresh weight of Silybum marianum(L.)Gaertn.and Mentha haplocalyx Briq.increased significantly compared to control.Results showed that lower concentration of NaCl could promote the growth of Silybum marianum(L.)Gaertn.and Mentha haplocalyx Briq..3、The chlorophyll content of Silybum marianum(L.)Gaertn.and Mentha haplocalyx Briq.has a positive response to salt stress.The chlorophyll levels of Silybum marianum(L.)Gaertn.increased with concentration of NaCl.And the chlorophyll levels of Mentha haplocalyx Briq.increased first and then decreased when concentration of NaCl increased.4、Under salt stress,the antioxidant enzyme of Silybum marianum(L.)Gaertn.and Mentha haplocalyx Briq.has a positive response.With the increasing of concentration of NaCl,SOD activity,POD activity,and CAT activity increased,which may remove excess reactive oxygen to protect Silybum marianum(L.)Gaertn.and Mentha haplocalyx Briq.,for excessive salt stress poison.MDA is final product of membrane lipid peroxidation which increased with the increasing of concentration of NaCl,and damaged the cell of Silybum marianum(L.)Gaertn.and Mentha haplocalyx Briq.5、Under salt stress,the content of soluble protein and proline of Silybum marianum(L.)Gaertn.and Mentha haplocalyx Briq.gradually increased to maintain the low osmotic potential of cell,thus resisted salt stress.6、Under salt stress,the concentration of sodium ion increased.But the concentration of calcium ion and potassium ion decreased,destroying the original ion homeostasis of Silybum marianum(L.)Gaertn.and Mentha haplocalyx Briq..